Back bias generating circuit

Abstract

A back bias generating circuit comprising a ring oscillator for generating a signal of alternating current waveform, a back bias generating section for generating a back bias voltage, the back bias generating section including first through third inverter gates for respectively inverting an output voltage from the ring oscillator, a pumping capacitor for inputting an output voltage from the third inverter gate at its one terminal, and a switching transistor for applying an output voltage at the other terminal of the pumping capacitor to a back bias terminal, the other terminal of the pumping capacitor being controlled, in accordance with a level of the output voltage from the ring oscillator, such that it is connected to a ground terminal to generate the back bias voltage, and switching transistor control section for controlling a voltage to be applied to the gate of the switching transistor in accordance with a level of the output voltage from the ring oscillator. In accordance with the present invention, the back bias generating circuit can reduce amount of electrons being injected from the pumping capacitor into a substrate so that malfunction of cells can be prevented, it is suitable for high speed operation and current consumption therein can be reduced.

Dependencies are inferred from the claim text.